EN 10217-7 Welded Stainless Steel Tube for Pressure Applications

Scope of EN 10217-7

EN 10217-7 is the stainless steel part of the European standard for welded steel tubes for pressure purposes. It specifies the technical delivery conditions for welded tubes made from corrosion-resistant austenitic and austenitic-ferritic steels that are intended to contain or convey fluids under pressure at room, elevated or sub-zero temperature.

The standard sits inside a family of documents. The EN 10217 series covers welded tubes, with parts 1 to 6 dealing with non-alloy and alloy steel grades, while the EN 10216 series covers the equivalent seamless product. Tubes ordered to EN 10217-7 are therefore the welded route to the same pressure duty that EN 10216-5 delivers in seamless form, and the choice between them is usually a question of diameter, wall thickness, cost and the acceptance of a longitudinal weld seam.

Manufacturing Route and Weld Configuration

Parameter	Details
Standard	EN 10217-7
Tube type	Welded stainless steel tubes for pressure purposes
Forming	Cold or hot forming of strip, followed by welding
Welding processes	TIG, laser or plasma, with the weld running longitudinally along the tube
Post-weld operations	Weld bead conditioning, cold reduction where specified, heat treatment and pickling
Outside diameter (OD)	6 mm to 1219 mm
Wall thickness	0.5 mm to 30 mm
Steel grades	1.4301 (304), 1.4307 (304L), 1.4404 (316L), 1.4571 (316Ti) and further grades listed in the standard
Delivery conditions	Solution annealed and pickled (AT), or cold-finished and pickled (TC1 and TC2)
Inspection and testing	Eddy current, hydrostatic, visual and dimensional inspection
Pressure equipment	Compliant with PED 2014/68/EU

Because the tube is formed from flat strip, the weld seam is an integral part of the product rather than an accessory. Mill practice therefore concentrates on three points: weld penetration control to avoid lack of fusion, protection of the seam from oxidation during welding, and a solution anneal that removes the residual stress and chromium depletion left by the thermal cycle.

Dimensional Range and Steel Grades

Outside diameter. From 6 mm capillary and instrument tubing up to 1219 mm large-diameter pipe for headers and vessels.

Wall thickness. From 0.5 mm thin-wall heat exchanger tube to 30 mm heavy-wall pressure pipe.

Length. Normally supplied in random or fixed lengths up to about 12 m, with longer lengths possible by agreement for specific projects.

Ends. Plain ends, bevelled ends or threaded ends depending on the joint design.

Surface. Pickled and passivated finish as standard, with bright annealed or polished finishes available where cleanliness matters.

The grade choice follows the corrosion duty rather than the mechanical duty for most stainless pressure service. 1.4301 and its low-carbon variant 1.4307 cover general aqueous and mildly oxidising media, 1.4404 adds molybdenum for chlorides and reducing acids, and the titanium-stabilised 1.4571 is used where elevated temperature service would otherwise cause carbide precipitation during welding.

Delivery Conditions, Inspection and Testing

Delivery condition determines both the mechanical state and the surface of the tube. Tubes are supplied solution annealed and pickled in condition AT, or cold finished in conditions TC1 and TC2. Cold finishing improves dimensional tolerance and surface finish but raises strength and reduces elongation, which is why the test certificate values must always be read together with the stated delivery condition.

Test or inspection	Typical method
Tensile testing	Room-temperature tensile test to confirm Rm, Rp0.2 and elongation
Leak and pressure integrity	Hydrostatic test, or an equivalent non-destructive test where specified
Weld seam examination	Automated eddy current testing across the full tube length
Weld seam radiography or ultrasonic examination	Applied when the order specifies it
Dimensional inspection	Outside diameter, wall thickness, ovality and length against the tolerance class ordered
Visual and surface inspection	Confirmation of freedom from harmful defects and adequate pickling

Ordering, Handling and Use

A complete EN 10217-7 enquiry identifies the outside diameter, wall thickness, grade, delivery condition, length, tolerance class, end finish, test category and, where pressure equipment rules apply, the required inspection certificate. Specification of the certificate up front avoids disputes at delivery, since the standard supports inspection documentation for pressure applications.

The tubes are used across chemical and petrochemical processing, pharmaceutical and biotechnology plants, food and beverage lines, power generation, heat exchangers and pressure vessels. Two fabrication rules apply throughout. First, stainless tube must be handled with stainless tools and kept away from carbon steel surfaces and chloride-bearing marking fluids, because contamination becomes a pitting site. Second, after welding, the heat tint should be removed and the joint pickled and passivated, since an oxidised heat affected zone has markedly lower corrosion resistance than the parent tube.

Frequently Asked Questions

Q: What is EN 10217-7 used for?
It is the delivery standard for welded stainless steel tubes in pressure-bearing service, covering heat exchanger tubing, process piping, instrument lines and pressure vessel connections.

Q: What is the difference between EN 10216-5 and EN 10217-7?
EN 10216-5 covers seamless stainless pressure tubes, while EN 10217-7 covers the welded product. Seamless tube avoids a longitudinal weld but is generally more expensive at large diameters.

Q: Which grades does EN 10217-7 cover?
The standard lists austenitic and austenitic-ferritic stainless grades including 1.4301 (304), 1.4307 (304L), 1.4404 (316L) and 1.4571 (316Ti).

Q: What does delivery condition AT mean?
AT denotes tubes that have been solution annealed and pickled. Cold-finished alternatives are supplied in conditions TC1 and TC2, with tighter dimensions and a different strength and elongation balance.

Q: What tests are carried out on EN 10217-7 tubes?
Tensile testing, hydrostatic or equivalent pressure testing, automated eddy current testing of the weld seam, dimensional inspection and visual examination, with radiography or ultrasonic testing added when ordered.

Q: Is EN 10217-7 suitable for PED pressure equipment?
Yes. Tubes supplied to EN 10217-7 are used in pressure equipment designed to PED 2014/68/EU, and the required inspection documentation should be stated on the order.